1. Technical Field
The present invention relates generally to query processing, and more specifically relates to a system and method for identifying predicates causing inefficient query processing, and proposing and implementing solutions to improve query performance.
2. Related Art
In an environment such as SAP BW (or any environment using star schema or complex SQL), determining the cause of slow query performance can be difficult. For instance, individual queries must be identified for analysis, and then the SQL must be captured, explained, and analyzed to determine the possible reason for the performance problem.
When end-users use drill-down in queries, additional predicates are added to the query SQL to support the grouping or selection in the drill-down. Predicates may include any element of a search condition that expresses or implies a comparison operation. This means that a user drill-down creates SQL with similar sets of predicates, which are usually based on a core set of required predicates packaged in the query. The addition (or removal) of predicates can cause changes in query performance. If, for example, a predicate which would filter well is added to a query, but the predicate is not applied early in query processing (due to missing catalog statistics, missing indexes, optimizer problems, etc.), then an automated method of finding the predicate(s) associated with the slow performance can help to reduce the effort necessary to solve the problem.
Unfortunately, there exist no automated query tools capable of determining how predicate usage impacts query performance. Accordingly, a need exists for a system and method that can both analyze predicate usage and propose solutions to improve query performance.